Canopies and other outdoor shade structures have been in existence through history. However, with the advent of improved mechanics and materials, a need has developed to provide canopies with more height, increased head room, lighter weight, easier to use, and increased portability.
U.S. Pat. No. 4,607,656, issued on Aug. 26, 1986, to Carter (expired), incorporated herein by reference, discloses an early collapsible canopy that was easier to use and required reduced room to store. The '656 patent specifically relates to a canopy that comprises a plurality of vertical legs connected by X shaped trusses. The X shaped trusses have a bottom portion slidably connected to the vertical legs allowing the plurality of vertical legs to be moved from a closed, stored position to an open, erect position without a complex connection between the various legs. U.S. Pat. No. 4,641,676, issued on Feb. 10, 1987, to Lynch (expired), incorporated herein by reference, discloses a similar canopy structure.
While the structures disclosed by the '656 and '676 patents provided improvement over then available portable canopies, which required complex construction and breakdown to use, both the '656 and '676 patents used X shaped trusses extending across the middle of the canopy to provide a support for a top cover. The horizontal X shaped truss extending across the middle of the canopy provided drawbacks, including, for example, the canopy had relatively low clearance. Many improvements have been derived from the original patents relating to canopies having X shaped trusses in an attempt to increase the head clearance of canopies. One particularly elegant design is highlighted by U.S. Pat. No. 4,779,635, issued Oct. 25, 1988, to Lynch. The '635 patent is similar to the above described designs, but provides a roof support member connected to at least one of the vertical legs with a cantilever support. Thus, the canopy still is collapsible into a compact unit for moving and storage, but when extended, the roof members automatically expands above the X shaped trusses. The cantilever provides a mechanism to automatically push the roof members from a folded or retracted position into an unfolded or extended position.
While the automatic roof structure of the '635 patent greatly increased headroom and enhanced the easy of operation of the portable device, the higher, angled roof structure tended to decrease the overall structure's stability and strength. Thus, it would be desirous to develop a canopy with an automatic roof structure that has improved structural stability and strength.